Flotation process



Patented Aug. 27, 1935 UNITED STATES PATENT OFFICE FLOTATION PROCESS Samuel Lenher, Wllmington, Del., asslgnor a E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application May 3, 1933, Serial No. 669,199

4 Claims.

This invention relates to a mineral flotation process, in particular to a flotation process utilizing as flotation agents normal primary straight chain aliphatic saturated or unsaturated alcohols having from 6 to 18 carbon atoms in the alkyl chain. In accordance with the present invention it has been discovered that in the flotation treatment of ores to separate the desired constituents therefrom liquid media containing normal primary saturated or unsaturated alcohols, either, alone or with other flotation agents, are effective to separate the gangue from the ore according to well known principles of froth flotation. It is well known in the art that alcohols and oils, such as turpineol, pine oil, and alcohols from the methanol synthesis, are flotation agents. It is also well known in the art that fatty acids, such as lauric acid, oleic acid and stearic acid, when used alone or in conjunction with other flotation agents, such as pine oil, cresylic acid, or sulfur containing organic compounds, are effective flotation agents.

One object of the invention comprises a process for the froth flotation of minerals involving the use of normal primary straight chain saturated and unsaturated alcohols having from 6 to 18 carbon atoms in the alkyl chain. Another object of the invention relates to the use of the mineral pulps containing soluble salts which will react with the higher fatty acids and will not react with corresponding normal primary saturated of unsaturated alcohols.

The alcohols used in accordance with the present invention contain alkyl radicals having from 6 to 18 carbon atoms of either saturated or unsaturated s ecific alcohols. This group comprises hex alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, and'the alcohols known as oleyl alcohol, ricinoleyl alcohol, and linoleyl alcohol. U. S. Patent No. 1,370,366 on the use of dihydric alcohols and pinacones as flotation agents has been noted but these are not referred to in the present invention.

The above noted alcohols which may be used in accordance with this invention may be prepared by the catalytic reduction of fats, oils, or free fatty acids according to methods described in the art.

While the object of the present invention is to treat ores generally in the presence of fatty alcohols, the process is applied with particular efliciency to the treatment of nonsulflde bearing ores, for example phosphate rock, limestone, bauxite, barytes, ilmenite, calcite, malachite, azurite and cassiterite.

The amount of fatty alcohol which can be used in the flotation machine may vary within wide limits. The action of the fatty alcohol will be what is known technically as the action of a collector. The amounts of fatty alcohol collector may vary from a fraction of a pound per ton (as low as 0.05 lb. per ton) to as high as 20 pounds per ton. The flotative efficiency of these alcohols depend to a certain extent on the particular alcohol which is being used, c. g., whether the alcohol is saturated or unsaturated. The alcohols can be used alone or can be used with frothing agents, such as pine oil, and they can be used with sulfur containing organic compounds as xanthates, thiocarbonates, and mercaptans. Flotation with fatty alcohols must be carried out above the melting points of the alcohols. The alcohols used in this invention are all insoluble in Water. It is essential that these agents, acting as collectors, should be used in the proper proportion with frothing agents. It is well known that collectors may be effective between certain critical concentrations. The mechanism of the fat alcohol collectors will not be the same as that of the fatty acids since in general there will be no chemical reaction between the fatty alcohol and the ore or gangue as is the case with the fatty acids. In general, it will be necessary to use frothing agents with these fat alcohols. The fat alcohols having 8 carbon atoms or less in the molecule do not build up foams or froths on liquids, but the saturated and unsaturated fatty alcohols having from 8 to 18 carbon atoms in the molecule build up froths themselves without the addition of frothing agents under certain conditions of agitation. In this flotation process the fat alcohols may be used as assistants or collectors in the flotation process described in Lenher application Serial No. 665,955, flled April 13, 1933. This application describes as new flotation agents, the salts of the reaction products resulting from the action of a strong normally sulfonating agent upon one of the alcohols described herein as being flotation agents, these reaction products comprising true sulfate esters. These alcohols may also be used in conjunction with soaps, i. e., the salts of fatty acids, or other soaplike flotation agents. These alcohols may be used in conjunction with the products of the reaction of both saturated and unsaturated fatty acids or fatty acid derivatives, having from 8 to 18 carbon.

' atoms in the molecule, that is free fatty acids,

their salts or acid chlorides and sulfonated simple aliphatic compounds, such as beta hydroxy ethane sulfonic acid, beta amino ethane sulfonic acid, their salts and the like.-

Many advantages follow from the practice of the present invention. The alcohols do not form metal salts as do the corresponding acids and ness in the water, in mineral pulps and to inorganic salts generally than are free fatty acids. These fatty alcohols can be used over a range of hydrogen ion concentrations from a pH=1:t'o

a'pH=12.

'I'he fat alcohols are composed of a non-polar hydrocarbon chain and a polar hydroxyl or primary alcohol group (CHzOH). The surface activity or collecting action of these compounds is due to the alcohol group. The alcohols-are adsorbed on the surface of mineral particles with the polar group directed toward the water. Mineral particles are therefore coated with an oily fllm. It is well known that these fllms are of the order of one molecule or less in thickness. The mineral particle coated with fat alcohol cannot be wetted by the water and is drawn into the gas-liquid interface in the flotation machine on which it is buoyed to the surface and is held there by the contraction of the water film with the oil particle.

The invention is not to be limited to the speciiic illustrations given above, since they may be varied to a considerable-extent depending on the type of material being treated and other conditions. I

Any variation from the above description which corresponds to the spirit of the invention, is intended to be included within the scope of the claims.

I claim:

1. In the froth flotation of ores by agitating and aerating an aqueous suspension of finely divided minerals the step which comprises conducting said flotation in the presence of both a flotation agent, comprising a salt of a sulfuric acid ester of a normal primary alcohol having from.

eight to eighteen carbon atoms in the molecule, and a free normal primary alcohol having from six to eighteen carbon atoms in the molecules v2.-In the froth flotation of ores by agitating hol having from eight to eighteen carbon atoms in the molecule, and a free normal primary -alco-= hol having from six to eighteen carbon atoms in the molecule.

3. In the froth flotation of ores by a tating and aerating an aqueous suspension of flnely divided minerals the step which, comprises 'con-' ducting said flotation in the presence of both a flotation agent, comprising a sodium salt of a sulfuric acid ester of a normal primary alcohol having from eight to eighteen carbon atoms in the molecule, and a free normal primary alcohol having from six to eighteen carbon atoms in the molecule.

4. In the froth flotation of ores by agitating and aerating an aqueous suspension of finely divided minerals the step which comprises conducting said flotation in the presence of both a flotation agent, comprising a sodium salt of a sulfuric acid ester of lauryl alcohol, and free lauryl alcohol.

- SAMUEL LENHER. 

